e4be85a0   
   From: joe@user.com   
      
   "Fooser"  wrote in message   
   news:95d3d031-cd9c-40ae-931c-e93a7f8a9621@x16g2000prd.googlegroups.com...   
   > Greetings all.   
   >   
   > I posted this thread in Yahoo Groups but it has stalled.  I'm hoping   
   > to get a little more feed back so I'm re-posting here.  Sorry for the   
   > duplication.   
   >   
   > I'm in the process of building a Model I disk system using components   
   > from different acquisitions.  Both the CPU and Expansion Interface   
   > have the DIN dongle, and I have a buffered CPU to EI cable.   
   >   
   > When I plug in just the CPU and monitor, I get 15k from the ?mem   
   > command.  When I add the EI, I get the garbage screen. When I hold the   
   > break key and press reset, same garbage screen.  If I'm not mistaken,   
   > holding down the break during reset should show the memory size screen   
   > and a ?mem should show the additional EI memory.  It does not... just   
   > garbage.   
   >   
   > I've replaced the two banks of memory on the EI several times thinking   
   > it was a memory issue... no difference. I have two buffered EI cables   
   > and have tried both.  I have also swapped out the power supplies.   
   >   
   > To help troubleshoot, I purchased a DIN dongled EI motherboard from   
   > eBay and have exactly the same issue.   
   >   
   > I have two other working Model I disk systems but have not actually   
   > attached drive 0 since the memory on the EI is not being recognized.   
   >   
   > I do turn on the EI before the CPU.  Any suggestions what to check   
   > next?  I wish I could test the memory outside of the TRS-80 but I'm   
   > not aware of a method.  I guess I could take the memory from on of the   
   > other working EI's but I hate to mess with a working system. :-)   
   >   
   > Thanks folks.   
   >   
   > Regards,   
   > Don Mankin   
      
   Make sure power is good on the EI.  I'd pull all memory out of it and see if   
   I could get a boot first without any additional memory.   
      
   The DIN cables took across RAS, MUX, and CAS.  But ONLY on the OLD EI, not   
   the EI with the DDU chip.  That version of the EI regenerated the signals to   
   the RAM.   
      
   Make sure you have power getting to the buffered EI.  I forget the pin, but   
   it should be at the end of the connector.   
      
   If I remember correctly, when the CPU sees the EI, it tries to boot from it.   
   When you see the garbage, you're seeing whatever happens to be there while   
   the system tries to reset and read from the FDC.  Holding down the break key   
   should tell the CPU to ignore the FDC boot and continue on without disk.   
   Hmm, try the CPU with the buffered cable attached but NOT the EI.  Without   
   the EI providing power to the buffered cable I think you should see the same   
   hang.   
      
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